Here are the typical Os errors, before SQL fails over to the passive node:

-Connection to the target was lost. The initiator will attempt to retry the connection.
-The initiator could not send an iSCSI PDU. Error status is given in the dump data.
-\\Device\\MPIODisk25 is currently in a degraded state. One or more paths have failed, though the process is now complete.

Has anyone seen this issue before?

This is a two node SQL2012 SP1 Cluster running on Windows2008r2 SP1 Os.